Single phase metastable alpha-AgVO3 microrods with high crystallinity, tetragonal rod-like microstructure, uniform particle size distribution, and good dispersion were synthesized by direct coprecipitation at room temperature. They are shown to be viable peroxidase mimics that catalyze the oxidation of 3,3', 5,5'-tetramethylbenzidine in the presence of H2O2. Kinetic analysis indicated typical Michaelis-Menten catalytic behavior. The findings were used to design a colorimetric assay for H2O2, best measured at 652 nm. The method has a linear response in the 60 to 200 mu M H2O2 concentration range, with a 2 mu M detection limit. Benefitting from the chemical stability of the microrods, the method is well reproducible. It also is easily performed and highly specific.